fix(input): correct lon mapping

api/rest/predictor.swagger.yml

@@ -375,6 +375,13 @@ components:
         profile, hand off to `fallback_index`, or clip to the boundary.
       properties:
         launch: { $ref: "#/components/schemas/Launch" }
+        dataset:
+          type: string
+          format: date-time
+          description: |
+            Forecast run to predict from, given as its epoch. Defaults to the
+            active dataset. The named run must be stored; a request for one that
+            is not is rejected rather than answered from a different run.
         direction:
           type: string
           enum: [forward, reverse]